Thread: Pointer problems :(

I'm having a hard time finding my segmentation faults. Can anyone help me out please?

Code:

#include <stdlib.h>
#include <strings.h>
#include <stdio.h>

typedef struct proc_struct proc_struct;

typedef struct proc_struct * proc_ptr;

proc_ptr ReadyList[6];

struct proc_struct {
   proc_ptr       next_proc_ptr;
   char           name[10];
   int            priority;
};

void enqueue(proc_ptr *front, proc_ptr ptr){
	if(*front == NULL)
		*front = ptr;
	else
	{
		proc_ptr p;
		for(p = *front; p != NULL; p = p->next_proc_ptr){}
		p = ptr;
	}
}

proc_ptr dequeue(proc_ptr *front){
	if(*front == NULL)
	{
		return NULL;
	}
	else
	{
		proc_ptr value =  *front;
		*front = (*front)->next_proc_ptr;
		return value;
	}
}


main()
{
	int i;
	for(i = 0; i < 6; i++)
		ReadyList[i] = NULL;

   proc_struct a,b;
	strcpy(a.name,  "hello");
	strcpy(b.name,  "bye");
	a.priority = 1;
	b.priority = 1;
    a.next_proc_ptr = NULL;
    b.next_proc_ptr = NULL;

   enqueue( &ReadyList[1], &a );
   enqueue( &ReadyList[1], &b );

   printf(" ReadyList[1] contains %s \n", ReadyList[1]->name);
   printf(" ReadyList[1]'s next contains %s \n", ReadyList[1]->next_proc_ptr->name);

   //printf("%s\n",dequeue(&ReadyList[1])->name);
}

ah the good ol to much in a for loop problem
your writing to something that doesn't exits right here

Code:

for(i = 0; i < 6; i++)

should be

Code:

for(i = 0; i < 5; i++)

yes but arrays start at 0 not at 1 woops nevermind
[edit] sorry its late im going to bed [/edit]

Originally Posted by ryptide

I've narrowed it down to here... What is wrong with this??

Code:

for(p = *front; p != NULL; p = p->next_proc_ptr){}

thanks for your help.

Nothing's wrong with it, if you want p to end up NULL at the end. Since I doubt that's what you had in mind, you'll probably want to be checkign "p->next_proc_pointer" in the termination segment of the for loop also, and once "p->next_proc_pointer" is NULL, then set that to the new pointer.

Quzah.